1. Field of the Invention
The present invention relates to vibrating gyroscopes and electronic apparatuses incorporating the same, and more specifically, it relates to a vibrating gyroscope for use in video cameras with image stabilization capabilities, car navigation systems, pointing devices, etc., and to an electronic apparatus incorporating the same.
2. Description of the Related Art
FIG. 10 is a fragmentary perspective view of a conventional vibrating gyroscope. The principles of the vibrating gyroscope 80 shown in FIG. 10 are disclosed in Japanese Unexamined Patent Application Publication No. 10-332379.
Referring to FIG. 10, the vibrating gyroscope 80 includes a vibrator 100, supporting members 804, 805, 806, and 807, and a frame 810. The vibrator 100 includes a first piezoelectric substrate 101 polarized in the thickness direction, a first detecting electrode 101a and a second detecting electrode 101b being formed on a first principal plane thereof, and a second piezoelectric substrate 102 polarized in the thickness direction, a driving electrode (not shown) being formed on a first principal plane thereof. A second principal plane of the first piezoelectric substrate 101 and a second principal plane of the second piezoelectric substrate 102 are laminated via an intermediary electrode 103. Furthermore, the supporting members 804 and 805 are provided at the positions where node points N1 and N2 of the vibrator 100 are projected on the first principal plane of the first piezoelectric substrate 101, and the supporting members 806 and 807 are provided at the positions where the node points N1 and N2 are projected on the first principal plane of the second piezoelectric substrate 102. The first detecting electrode 101a is connected to the supporting member 804, the second detecting electrode 101b is connected to the supporting member 805, and the driving electrode on the first principal plane of the second piezoelectric substrate 102 is connected to the supporting members 806 and 807. The supporting members 804, 805, 806, and 807 are composed of the same material, are constructed in the same shape, and have the same stiffness, and support the piezoelectric substrates 101 and 102 while also serving as leads.
The frame 810 is composed of an insulating material such as resin, and has an upper face 810a on the same plane as the first principal plane of the first piezoelectric substrate 101, a lower face 810b on the same plane as the first principal plane of the second piezoelectric substrate 102, and projections 811 provided on an inner face of the frame 810 with a particular spacing along the width direction of the vibrator 100. Ends 804a, 805a, 806a, and 807a of the supporting members 804, 805, 806, and 807 extend in a direction parallel to the first principal plane of the first piezoelectric substrate 101 or the first principal plane of the second piezoelectric substrate 102. The ends 804a and 805b are fixed to the upper face 810a of the frame 810, for example, by soldering, and the ends 806a and 807a are fixed to the lower face 810b of the frame 810, for example, by soldering.
Generally, a vibrating gyroscope requires thick supporting members in order to prevent problems such as the vibrator falling off from the supporting members due to an excessive shock exerted on the vibrating gyroscope. Use of thick supporting members, however, causes the vibration of the vibrator to leak from the supporting members, reducing the magnitude of the vibration.
In the vibrating gyroscope 80, thin supporting members 804 and 806 are provided so as to sandwich the node point N1, and thin supporting members 805 and 807 are provided so as to sandwich the node point N2, and the supporting members 804, 805, 806, and 807 are fixed to the substrate 810 having the same thickness as the piezoelectric substrates 101 and 102. Thus, although supported by the thin supporting members 804, 805, 806, and 807, the vibrator 100 avoids problems such as falling off from the supporting members 804, 805, 806, and 807.
In the vibrating gyroscope 80 so constructed, when a driving signal is applied to the driving electrode on the first principal plane of the second piezoelectric substrate 102 via the supporting members 806 and 807, longitudinal-bar flexural oscillation occurs in the thickness direction of the vibrator 100, in which the nodes in the lowest mode are the node points N1 and N2. When an angular velocity, for which the longitudinal direction of the vibrator 100 is the axis, is applied to the vibrating gyroscope 80, the vibrator 100 is flexed in the width direction, and signals output from the first detecting electrode 101 a and the second detecting electrode 101b are processed, so that the angular velocity applied to the vibrating gyroscope is determined.
Furthermore, in the vibrating gyroscope 80, the projections 811 are provided with a particular spacing along the width direction of the vibrator 100, so that excessive displacement of the vibrator 100 and plastic deformation of the supporting members 804, 805, 806, and 807 are prevented even if an excessive shock in the width direction of the vibrator 100 is exerted on the vibrating gyroscope 80.
Next, FIG. 11 is a fragmentary exploded perspective view of another conventional vibrating gyroscope. In FIG. 11, components identical to or equivalent to those in the vibrating gyroscope 80 shown in FIG. 10 are indicated by the same reference characters, and description thereof is omitted.
Referring to FIG. 11, a vibrating gyroscope 90 includes a frame 820 instead of the frame 810 in the vibrating gyroscope 80, a substrate 830 (not shown in FIG. 10), a lower lid 840, and an upper lid (not shown) having the same construction as the lower lid 840.
The frame 820 is composed of resin, and includes an upper face 820a on a plane above a first principal plane of a first piezoelectric substrate 101, a lower face 820b on a plane below a first principal plane of a second piezoelectric substrate 102, and in addition, convex portions 812 provided on inner faces of the frame 820, and concave slots 813 provided on the upper face 820a and the lower face 820b of the frame 820. Supporting members 804 and 805 are led into the frame 820 from the top faces of the convex portions 812, supporting members 806 and 807 are led into the frame 820 from side faces of the convex portions 812, and ends 805a and 807a and ends 804a and 806a (not shown) of the supporting members 804, 805, 806, and 807 are pulled out from side faces of the convex portions 812.
The substrate is provided with lands 831, 832, 833, and 834 formed on the top face thereof, and electronic components mounted on the bottom face thereof, necessary for driving a vibrator 100 (not shown) or for determining angular velocity. The substrate 830 is fixed to the frame 820 so as to engage with the bottom faces of the convex portions 812 and with the inner faces of the frame 820. The ends 804a, 805a, 806a, and 807a of the supporting members 804, 805, 806, and 807 are connected to the lands 831, 832, 833, and 834. The upper lid and the lower lid 840 are composed of resin, and are provided with third projections 841. The upper lid and the lower lid 840 are fixed to the frame 820 so that the third projections 841 and the concave slots 813 of the frame 820 engage with each other.
In the vibrating gyroscope 90, the vibrator 100 is fixed to the frame 820 and the substrate 830 is also fixed to the frame 820, so that the vibrator 100, the frame 820, and the substrate 830 are integrated. Furthermore, the upper lid and the lower lid 840 are provided so as to seal the electronic components mounted on the substrate 830, electrically shielding the electronic components from the outside.
In the conventional vibrating gyroscope 80, thin supporting members 804, 805, 806, and 807 are provided so as to sandwich the node points N1 and N2 of the vibrator 100, and are fixed to the frame 810 having the same thickness as the piezoelectric substrates 101 and 102. Thus, there is no problem that the vibration of the vibrator 100 will be damped, and even if thin supporting members are used, problems such as the vibrator 100 falling off from the supporting members 804, 805, 806, and 807 are unlikely.
In the conventional vibrating gyroscope 80 shown in FIG. 10, however, there is a problem that the number of parts is increased because the frame 810 is included.
Furthermore, if the supporting members 804, 805, 806, and 807 are fixed to the frame 810 using solder, friction occurs between the supporting members 804, 805, 806, and 807 and the frame 810 in proximity to the ends 804a, 805a, 806a, and 807a that were fixed using solder, the friction causing a problem that the vibration of the vibrator 100 is disturbed.
Furthermore, in the conventional vibrating gyroscope 90 shown in FIG. 11, when the vibrator 100 and the substrate 830 are integrated, the frame 820 composed of resin is included, causing a problem that the overall size of the vibrating gyroscope is increased.
In particular, if the area of the entire vibrating gyroscope is determined in product specifications, the area of the substrate 830 is restricted and the need arises to mount the vibrator 100 and required electronic components on the top face and the bottom face of the substrate 830, causing a problem in the increased height of the overall vibrating gyroscope. Furthermore, when the electronic components are mounted on the bottom face of the substrate 130, the lower lid 840 must be provided in order to seal in the electronic components, causing the problems in the further increase height of the overall vibrating gyroscope and an increase in the number of parts.
Furthermore, the manufacturing process for three-dimensionally constructing the frame 820 and the supporting members 804, 805, 806, and 807 is very complex, causing a problem of laborious production.
Accordingly, it is an object of the present invention to provide a vibrating gyroscope in which the number of parts is reduced.
It is another object of the present invention to provide a vibrating gyroscope in which the a real size and the height are reduced.
It is still another object of the present invention to provide an electronic apparatus in which the cost and size are reduced owing to a reduction in the number of parts and smaller size of the vibrating gyroscope.
In order to achieve the above objects, a vibrating gyroscope according to the present invention comprises a substrate, a vibrator, and supporting members fixed in proximity to the node points on both principal planes of the vibrator. The supporting members comprise first portions extending in a direction parallel to the substrate from the principal planes of the vibrator, and second portions extending in a direction orthogonal to the substrate, the second portions being fixed to the substrate.
The vibrating gyroscope according to the present invention is also characterized in that the second portions are disposed in proximity to the vibrator, and in that the second portions inhibit excessive displacement of the vibrator when the vibrator is excessively displaced.
The vibrating gyroscope according to the present invention is also characterized in that the second portions comprise projections, which are disposed in proximity to the vibrator and which inhibit excessive displacement of the vibrator when the vibrator is excessively displaced.
The vibrating gyroscope according to the present invention is also characterized in that the second portions comprise bent portions bent back in a direction orthogonal to the substrate.
The vibrating gyroscope according to the present invention is also characterized in that the supporting members are composed of a hard elastic material.
The vibrating gyroscope according to the present invention is also characterized in that it includes driving means for vibrating the vibrator, and detecting means for detecting an output generated by the vibrator.
The vibrating gyroscope according to the present invention is also characterized in that electronic components are mounted on the substrate only on the face on which the vibrator is mounted, and in that a case is fixed on the substrate so as to cover the vibrator and the electronic components.
The vibrating gyroscope according to the present invention is also characterized in that the substrate comprises through holes at the ends thereof.
An electronic apparatus according to the present invention is characterized by comprising the vibrating gyroscope.
In the vibrating gyroscope according to the present invention, the vibrator is supported by being sandwiched from above and below the node points N1 and N2, so that the vibration of the vibrator is inhibited from leaking from the supporting members, and so that the vibrator is inhibited from falling off from the supporting members even if an excessive shock is exerted thereon.
Furthermore, in the vibrating gyroscope according to the present invention, the second portions are provided in proximity to the vibrator, so that the supporting members are not susceptible to plastic deformation even if an excessive shock is exerted thereon.
Furthermore, the vibrating gyroscope according to the present invention has a reduced number of parts because it does not include a frame.
Furthermore, the vibrating gyroscope according to the present invention allows adjustment of the stiffness of the supporting members through coordination of the length of the bent portions provided in the second portions. Thus, the stiffness of the supporting members provided on the upper face of the vibrator and the stiffness of the supporting members provided on the lower face of the vibrator can be made equal, so that the vibrator is allowed to vibrate freely, serving to accurately determine angular velocity.
Furthermore, the vibrating gyroscope according to the present invention allows the vibrator to be fixed on the substrate for integration without using any upper lid, lower lid, or frame. Therefore, because the upper lid, lower lid, and frame are not included, the size of the overall vibrating gyroscope is reduced, the height is decreased, and the number of parts is reduced.
Furthermore, the vibrating gyroscope according to the present invention, in which the bottom face of the substrate is not electrically connected to any electronic component, can be used as a surface-mounted component by affixing a case on the substrate and providing through holes at the ends of the substrate.
Furthermore, the vibrating gyroscope according to the present invention, which has a metallic case, allows it to be smaller and allows shielding of the electronic components from external electromagnetic waves.
Furthermore, the vibrating gyroscope according to the present invention is smaller because no frame is included, so that the area on the substrate for mounting the components and for lands can be increased.
Furthermore, the electronic apparatus according to the present invention is of reduced cost and smaller size owing to a reduction in the number of parts and smaller size of the vibrating gyroscope.
For the purpose of illustrating the invention, there is shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.